Third-order intermodulation distortion in capacitively-driven VHF micromechanical resonators

Abstract

Substantial increases by more than 22 dB in the third-order input intercept points (IIP3) of capacitively trans- duced MEMS-based vibrating micromechanical resonators have been attained by using contour-mode disk geometries to replace previous clamped-clamped beam versions. Specifically, a 156-MHz contour-mode disk resonator with Q = 20,500 exhibits a measured IIP3 = 19.49 dBm, which is substantially better than the -3 dBm previously measured for a 10-MHz clamped-clamped beam resonator, and which now erases any lingering skepticism regarding the linearity of micro-scale mechanical resonators. Indeed, with IIP3's about 20 dBm, high Q communication filters using the micromechanical resonators of this work should now be able to replace present-day receive path filters with little degra- dation (only 0.11 dB) in cumulative receiver IIP3.